It's all about the components of forces (there is no such thing as a scalar force, all forces have a magnitude and a direction, making them vectors, in which case they have components in different directions).
The weight of the person on the tyrolean is balanced by the vertical components of the tension in each side of the rope, each of which is balanced by the force applied to the rope by the anchor at that end. Regardless of where you are on the tyrolean, the tension in the rope is equal on either side of you (if it wasn't it would just slide through the pulley), hence the forces on the anchors are equal. And since there are two "anchor" forces whose vertical components are balancing your weight, each only feels half of your equivalent load. The surprising thing is that since the tension is equal to the load on the anchors, the rope only feels half of your equivalent load as well (maybe its not that surprising since you do have two bits of rope supporting you; think of the limiting case where the anchors are both in the same spot, so the angle is zero).
So in answer to Tom's question, the anchors are feeling the same "pain" as the rope. |